KVM: VMX: Split out the non-virtualization part of vmx_interrupt_blocked()

Move the non-VMX chunk of the "interrupt blocked" checks to a separate
helper so that KVM can reuse the code to detect if interrupts are blocked
for L2, e.g. to determine if a virtual interrupt _for L2_ is a valid wake
event.  If L1 disables HLT-exiting for L2, nested APICv is enabled, and L2
HLTs, then L2 virtual interrupts are valid wake events, but if and only if
interrupts are unblocked for L2.

Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20240607172609.3205077-4-seanjc@google.comSigned-off-by: Sean Christopherson <seanjc@google.com>

arch/x86/kvm/vmx/vmx.c

@@ -5049,14 +5049,19 @@ int vmx_nmi_allowed(struct kvm_vcpu *vcpu, bool for_injection)
 	return !vmx_nmi_blocked(vcpu);
 }
 
+bool __vmx_interrupt_blocked(struct kvm_vcpu *vcpu)
+{
+	return !(vmx_get_rflags(vcpu) & X86_EFLAGS_IF) ||
+	       (vmcs_read32(GUEST_INTERRUPTIBILITY_INFO) &
+		(GUEST_INTR_STATE_STI | GUEST_INTR_STATE_MOV_SS));
+}
+
 bool vmx_interrupt_blocked(struct kvm_vcpu *vcpu)
 {
 	if (is_guest_mode(vcpu) && nested_exit_on_intr(vcpu))
 		return false;
 
-	return !(vmx_get_rflags(vcpu) & X86_EFLAGS_IF) ||
-	       (vmcs_read32(GUEST_INTERRUPTIBILITY_INFO) &
-		(GUEST_INTR_STATE_STI | GUEST_INTR_STATE_MOV_SS));
+	return __vmx_interrupt_blocked(vcpu);
 }
 
 int vmx_interrupt_allowed(struct kvm_vcpu *vcpu, bool for_injection)

arch/x86/kvm/vmx/vmx.h

@@ -406,6 +406,7 @@ u64 construct_eptp(struct kvm_vcpu *vcpu, hpa_t root_hpa, int root_level);
 bool vmx_guest_inject_ac(struct kvm_vcpu *vcpu);
 void vmx_update_exception_bitmap(struct kvm_vcpu *vcpu);
 bool vmx_nmi_blocked(struct kvm_vcpu *vcpu);
+bool __vmx_interrupt_blocked(struct kvm_vcpu *vcpu);
 bool vmx_interrupt_blocked(struct kvm_vcpu *vcpu);
 bool vmx_get_nmi_mask(struct kvm_vcpu *vcpu);
 void vmx_set_nmi_mask(struct kvm_vcpu *vcpu, bool masked);